Implement screen capture for android

content/browser/media/capture/web_contents_video_capture_device.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Implementation notes: This needs to work on a variety of hardware
 // configurations where the speed of the CPU and GPU greatly affect overall
 // performance. Spanning several threads, the process of capturing has been
 // split up into four conceptual stages:
 //
 //   1. Reserve Buffer: Before a frame can be captured, a slot in the client's
@@ skipping 200 matching lines @@
                       const base::Callback<void(bool)>& done_cb);
 
 // Renews capture subscriptions based on feedback from WebContentsTracker, and
 // also executes copying of the backing store on the UI BrowserThread.
 class WebContentsCaptureMachine : public VideoCaptureMachine {
  public:
   WebContentsCaptureMachine(int render_process_id, int main_render_frame_id);
   ~WebContentsCaptureMachine() override;
 
   // VideoCaptureMachine overrides.
-  bool Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
-             const media::VideoCaptureParams& params) override;
+  void Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+             const media::VideoCaptureParams& params,
+             const base::Callback<void(bool)> callback) override;
   void Stop(const base::Closure& callback) override;
 
   // Starts a copy from the backing store or the composited surface. Must be run
   // on the UI BrowserThread. |deliver_frame_cb| will be run when the operation
   // completes. The copy will occur to |target|.
   //
   // This may be used as a ContentCaptureSubscription::CaptureCallback.
   void Capture(const base::TimeTicks& start_time,
                const scoped_refptr<media::VideoFrame>& target,
                const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
                    deliver_frame_cb);
 
  private:
+  bool InternalStart(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+                     const media::VideoCaptureParams& params);
+  void InternalStop(const base::Closure& callback);
   bool IsStarted() const;
 
   // Computes the preferred size of the target RenderWidget for optimal capture.
   gfx::Size ComputeOptimalTargetSize() const;
 
   // Response callback for RenderWidgetHost::CopyFromBackingStore().
   void DidCopyFromBackingStore(
       const base::TimeTicks& start_time,
       const scoped_refptr<media::VideoFrame>& target,
       const RenderWidgetHostViewFrameSubscriber::DeliverFrameCallback&
@@ skipping 229 matching lines @@
       tracker_(new WebContentsTracker(true)),
       weak_ptr_factory_(this) {}
 
 WebContentsCaptureMachine::~WebContentsCaptureMachine() {}
 
 bool WebContentsCaptureMachine::IsStarted() const {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   return weak_ptr_factory_.HasWeakPtrs();
 }
 
-bool WebContentsCaptureMachine::Start(
+void WebContentsCaptureMachine::Start(
+    const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+    const media::VideoCaptureParams& params,
+    const base::Callback<void(bool)> callback) {
+  // Starts the capture machine asynchronously.
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&WebContentsCaptureMachine::InternalStart,
+                 base::Unretained(this),
+                 oracle_proxy,
+                 params),
+      callback);
+}
+
+bool WebContentsCaptureMachine::InternalStart(
     const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
     const media::VideoCaptureParams& params) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(!IsStarted());
 
   DCHECK(oracle_proxy.get());
   oracle_proxy_ = oracle_proxy;
   capture_params_ = params;
 
   render_thread_.reset(new base::Thread("WebContentsVideo_RenderThread"));
   if (!render_thread_->Start()) {
     DVLOG(1) << "Failed to spawn render thread.";
     render_thread_.reset();
     return false;
   }
 
   // Note: Creation of the first WeakPtr in the following statement will cause
   // IsStarted() to return true from now on.
   tracker_->Start(initial_render_process_id_, initial_main_render_frame_id_,
                   base::Bind(&WebContentsCaptureMachine::RenewFrameSubscription,
                              weak_ptr_factory_.GetWeakPtr()));
 
   return true;
 }
 
 void WebContentsCaptureMachine::Stop(const base::Closure& callback) {
+  // Stops the capture machine asynchronously.
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE, base::Bind(
+          &WebContentsCaptureMachine::InternalStop,
+          base::Unretained(this),
+          callback));
+}
+
+void WebContentsCaptureMachine::InternalStop(const base::Closure& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   if (!IsStarted()) {
     callback.Run();
     return;
   }
 
   // The following cancels any outstanding callbacks and causes IsStarted() to
   // return false from here onward.
   weak_ptr_factory_.InvalidateWeakPtrs();
@@ skipping 198 matching lines @@
     scoped_ptr<Client> client) {
   DVLOG(1) << "Allocating " << params.requested_format.frame_size.ToString();
   core_->AllocateAndStart(params, client.Pass());
 }
 
 void WebContentsVideoCaptureDevice::StopAndDeAllocate() {
   core_->StopAndDeAllocate();
 }
 
 }  // namespace content